Osisko Windfall Drilling Returns 3,979 g/t Au Over 2.3 Metres

TORONTO, Oct. 05, 2021 (GLOBE NEWSWIRE) — Osisko Mining Inc. (OSK:TSX. “Osisko” or the “Corporation”) is pleased to provide new analytical results from the ongoing drill program at its 100% owned Windfall gold project located in the Abitibi greenstone belt, Urban Township, Eeyou Istchee James Bay, Québec.

Significant new analytical results presented below include 40 intercepts in 15 drill holes (7 from surface, 8 from underground) and 13 wedges. The infill intercepts are located inside defined February 2021 mineral resource estimate (“MRE”) blocks (

see Osisko news release dated February 17,


2021

). The expansion intercepts are located outside the February 2021 MRE blocks and either expand resource wireframes or are in a defined zone or corridor but do not yet correlate to a specific wireframe.

Osisko Chief Executive Officer John Burzynski commented: “Windfall continues to deliver high-grade values. Today’s spectacular headline result includes a sub-interval of over 15 kilograms per tonne gold and is the second highest sample ever recorded at Windfall (

see Osisko news release date December 1, 2020

). Our resource infill and expansion drill program has continuously demonstrated the high-grade nature of the Windfall deposit.”

Selected high-grade intercepts include:

3979 g/t Au over 2.3 metres

in OSK-W-21-2565;

118 g/t Au over 3.4 metres

in WST-21-0763A;

110 g/t Au over 2.3 metres

and

79.7 g/t Au over 2.0 metres

in WST-21-0858A;

82.7 g/t Au over 2.2 metres

in OSK-W-21-1949-W8;

25.6 g/t Au over 4.2 metres

in OSK-W-21-2551-W3; and

35.8 g/t Au over 2.9 metres

in OSK-W-21-2564-W1. Maps showing hole locations and full analytical results are available at


www.osiskomining.com


.



Infill Drilling


Hole No.

From


(m)

To


(m)

Interval (m)

Au (g/t) uncut

Au (g/t) cut to 100 g/t

Zone

Corridor

OSK-W-21-1432-W6

879.6

881.6

2.0

8.62

LX4_3424


Lynx 4


including
879.6 880.2 0.6 28.7

OSK-W-21-1432-W7

1045.0

1047.0

2.0

13.4

LX4_3430


Lynx 4


including
1045.7 1046.4 0.7 28.4

OSK-W-21-1827-W5

877.0

879.0

2.0

5.25

UDD_4100

Underdog

OSK-W-21-1949-W8

1069.8

1072.0

2.2

82.7

32.0

LX4_3430


Lynx 4


including
1071.0 1071.6 0.6 286 100

OSK-W-21-2287-W3

1158.5

1161.5

3.0

5.00

LX4_3446

Lynx 4

OSK-W-21-2503-W5

934.0

936.0

2.0

14.6

TLX_3163


Triple Lynx


including
934.9 935.2 0.3 82.5

OSK-W-21-2544

914.0

916.5

2.5

7.51

TLX_3194


Triple Lynx


including
914.6 915.6 1.0 18.4

OSK-W-21-2551-W3

867.4

871.6

4.2

25.6

LX4_3414


Lynx 4


including
867.9 868.4 0.5 84.2

OSK-W-21-2560

349.9

352.0

2.1

9.71

Z27_1123

Zone 27


355.0

357.0

2.0

40.1

Z27_1102


Zone 27


including
355.7 356.3 0.6 91.4


370.1

372.5

2.4

5.09

Z27_1115


Zone 27


including
370.1 371.0 0.9 10.7

OSK-W-21-2564-W1

784.5

787.4

2.9

35.8

TLX_3159

Lynx HW


902.0

904.0

2.0

6.70

TLX_3194

Triple Lynx

OSK-W-21-2577

797.6

799.6

2.0

5.68

Z27_1108

Zone 27

OSK-W-21-2581

257.0

259.0

2.0

5.28

CA1_2500


Caribou


including
257.4 258.0 0.6 16.5


469.0

471.0

2.0

14.6

Z27_1115

Zone 27


476.5

480.0

3.5

3.96

Z27_1115

Zone 27

WST-21-0763A

472.6

476.0

3.4

118

41.9

LX4_3430


Lynx 4


including
472.6 473.5 0.9 386 100

WST-21-0771C

313.4

317.0

3.6

3.90

LSW_3556


Lynx SW


including
313.4 313.8 0.4 21.4

and
316.6 317.0 0.4 12.0

WST-21-0855

172.0

174.1

2.1

18.1

LXM_3304


Lynx


including
173.8 174.1 0.3 95.3

WST-21-0858A

180.2

182.5

2.3

110

44.3

LXM_3304


Lynx


including
181.0 181.3 0.3 607 100


517.0

519.0

2.0

79.7

28.3

LX4_3430


Lynx 4


including
518.1 518.5 0.4 357 100

WST-21-0877

305.6

307.7

2.1

4.37

Lynx SW


Lynx SW


including
305.6 305.9 0.3 28.7

Notes: True widths are estimated at 55 – 80% of the reported core length interval. See

“Quality Control and Reporting Protocols”

below., LXM = Lynx Main, LX4 = Lynx 4, LSW = Lynx Southwest, TLX = Triple Lynx, UDD = Underdog, CA1 = Caribou, and Z27 = Zone 27.



Expansion Drilling


Hole No.

From


(m)

To


(m)

Interval (m)

Au (g/t) uncut

Au (g/t) cut to 100 g/t

Zone

Corridor

OSK-W-17-841

966.3

968.8

2.5

11.2

Underdog

Underdog

OSK-W-21-1432-W7

1053.0

1055.1

2.1

13.5

Lynx 4


Lynx


including
1053.0 1054.0 1.0 27.5

OSK-W-21-1827-W6

1084.0

1086.0

2.0

4.75

Underdog


Underdog


including
1084.8 1085.3 0.5 18.9

OSK-W-21-1871-W1

561.7

564.2

2.5

10.8

Caribou


Caribou


including
563.4 564.2 0.8 30.8

OSK-W-21-2503-W5

1004.0

1006.0

2.0

36.4

22.6

Triple Lynx


Triple Lynx


including
1004.7 1005.0 0.3 193 100

OSK-W-21-2532-W1

703.0

705.1

2.1

3.50

Underdog


Underdog


including
704.7 705.1 0.4 17.6

OSK-W-21-2540-W2

1149.0

1151.0

2.0

5.93

Triple Lynx

Triple Lynx

OSK-W-21-2548-W1

488.0

490.0

2.0

15.9

Caribou


Caribou


including
488.0 489.0 1.0 31.8

OSK-W-21-2561

611.2

613.5

2.3

9.05

Triple Lynx


Triple Lynx


including
612.3 612.8 0.5 41.2

OSK-W-21-2565

535.8

538.1

2.3

3979

27.2

Caribou


Caribou


including
537.5 538.1 0.6 15250 100

OSK-W-21-2577

593.0

595.0

2.0

6.61

Caribou

Caribou

OSK-W-21-2581

188.4

191.0

2.6

6.65

Caribou


Caribou


including
189.8 190.6 0.8 13.8

WST-21-0771C

222.0

225.2

3.2

7.83

Lynx SW


Lynx SW


including
224.7 225.2 0.5 31.5

WST-21-0834B

302.0

304.0

2.0

3.54

Lynx HW


Lynx HW


including
302.0 302.4 0.4 17.5

WST-21-0874

253.0

255.2

2.2

6.25

Triple Lynx

Triple Lynx

WST-21-0881A

247.5

249.5

2.0

12.2

Lynx SW

Lynx SW


444.3

446.3

2.0

5.25

Lynx SW


Lynx SW


including
444.8 445.2 0.4 26.1

Notes: True widths are estimated at 55 – 80% of the reported core length interval. See

“Quality Control and Reporting Protocols”

below. HW= Hanging wall and SW = Southwest



Drill hole location


Hole Number

Azimuth (°)

Dip


(°)

Length (m)

UTM E

UTM N

Elevation

Section

OSK-W-17-841
330 -60 1032 452689 5434702 397 2800

OSK-W-21-1432-W6
132 -55 1065 453811 5435779 400 4300

OSK-W-21-1432-W7
132 -55 1185 453811 5435779 400 4300

OSK-W-21-1827-W5
331 -58 1203 452506 5434390 403 2475

OSK-W-21-1827-W6
331 -58 1281 452506 5434390 403 2475

OSK-W-21-1871-W1
331 -56 612 452496 5434397 402 2475

OSK-W-21-1949-W8
105 -57 1284 453440 5435479 401 3825

OSK-W-21-2287-W3
116 -53 1368 453607 5435714 404 4075

OSK-W-21-2503-W5
126 -58 1211 453333 5435641 413 3800

OSK-W-21-2532-W1
341 -60 1035 452480 5434428 401 2475

OSK-W-21-2540-W2
117 -60 1314 453465 5435640 410 3925

OSK-W-21-2544
128 -50 1161 452960 5435539 419 3425

OSK-W-21-2548-W1
331 -57 837 452829 5434550 398 2850

OSK-W-21-2551-W3
120 -55 954 453622 5435635 405 4050

OSK-W-21-2560
333 -53 684 452404 5434674 400 2525

OSK-W-21-2561
142 -51 801 452886 5435484 409 3350

OSK-W-21-2564-W1
132 -50 1152 452960 5435539 419 3425

OSK-W-21-2565
136 -57 717 452768 5435312 406 3150

OSK-W-21-2577
325 -52 822 452829 5434550 398 2850

OSK-W-21-2581
333 -49 755 452469 5434627 403 2550

WST-21-0763A
120 -39 567 453507 5435332 -47 3800

WST-21-0771C
127 -52 357 452954 5435003 252 3175

WST-21-0834B
114 -23 378 453463 5435327 32 3775

WST-21-0855
122 -44 265 453506 5435332 -48 3800

WST-21-0858A
118 -41 643 453507 5435332 -48 3800

WST-21-0874
137 -63 403 453508 5435327 -7 3800

WST-21-0877
158 -60 490 453104 5435065 231 3325

WST-21-0881A
147 -57 457 453105 5435065 231 3325


Caribou Zone


Mineralization most commonly occurs in gold-bearing pyrite stockworks as well as semi-massive pyrite replacement zones associated with phyllic alteration (sericite-pyrite ± silica) with sulphides, pyrite dominated with minor chalcopyrite and sphalerite ranging from trace to up to 20%, and local visible gold. Mineralization is hosted in rhyolites or mafic-intermediate volcanics frequently at or near faults or the contact with felsic porphyritic intrusions.


Underdog


Mineralization most commonly occurs in gold-bearing quartz-pyrite (± tourmaline) veins and as disseminated, stringer, semi-massive to massive pyrite with minor sphalerite, chalcopyrite and molybdenite associated with strong sericite and silica alteration. Mineralization is hosted along the intrusive contacts of a three-phase composite felsic porphyritic unit which cross-cuts felsic and mafic volcanic sequences.


Zone 27


Mineralization most commonly occurs as replacement-type characterized by 5% to 50% disseminated, stringer, semi-massive or stockwork pyrite, ptygmatic tourmaline veins, quartz-tourmaline crustiform veins, local quartz-carbonate veins, and local visible gold. Mineralization is associated with moderate to strong sericite, weak to strong silica, weak chlorite and carbonate and locally weak fuchsite and is hosted in strongly altered andesites, in or at the contact of the rhyolite, or along the contacts with felsic porphyritic intrusions.


Lynx Zone


Mineralization occurs as grey to translucent quartz-carbonate-pyrite-tourmaline veins and pyrite replacement zones and stockworks. Vein-type mineralization is associated with haloes of pervasive sericite-pyrite ± silica alteration and contain sulphides (predominantly pyrite with minor amounts of chalcopyrite, sphalerite, galena, arsenopyrite, and pyrrhotite) and local visible gold. Replacement mineralization is associated with strong pervasive silica-sericite-ankerite ± tourmaline alteration and contains disseminated pyrite from trace to 80% with local visible gold. Pyrite stockworks can form envelopes that reach several tens of metres thick. Fuchsite alteration is common and is spatially constrained to near the gabbros. Mineralization occurs at or near geological contacts between felsic porphyritic or fragmental intrusions and the host rhyolites or gabbros and locally can be hosted along the gabbro-rhyolite contact.


Qualified Person



The scientific and technical content of this news release has been reviewed, prepared and approved by Mr. Louis Grenier, M.Sc.A., P.Geo. (OGQ 800), Director of Exploration for Osisko’s Windfall gold project, who is a “qualified person” as defined by National Instrument 43-101 – Standards of Disclosure for Mineral Projects (“NI 43-101”).


Quality Control and Reporting Protocols



True


width


determination


is


estimated


at


55-80%


of


the


reported


core


length


interval


for


the


zone.


Assays


are


uncut


except


where indicated. Intercepts occur within geological confines of major zones but have not been correlated to individual vein domains at this time. Reported intervals include minimum weighted averages of 3.5 g/t Au diluted over core lengths of at least 2.0 metres. NQ core assays were obtained by either 1-kilogram screen fire assay or standard 50-gram fire-assaying-AA finish or gravimetric finish at (i) ALS Laboratories in Val d’Or, Québec, Vancouver, British Colombia, Lima, Peru or Vientiane, Laos (ii) Bureau Veritas in Timmins, Ontario. The 1-kilogram screen assay method is selected by the geologist when samples contain coarse gold or present a higher percentage of pyrite than surrounding intervals. Selected samples are also analyzed for multi-elements, including silver, using a Four Acid Digestion-ICP-MS method at ALS Laboratories. Drill program design, Quality Assurance/Quality Control (“QA/QC”) and interpretation of results is performed by qualified persons employing a QA/QC program consistent with NI 43-101 and industry best practices. Standards and blanks are included with every 20 samples for QA/QC purposes by the Corporation as well as the lab. Approximately 5% of sample pulps are sent to secondary laboratories for check assay.


About the Windfall Gold Deposit



The Windfall gold deposit is located between Val-d’Or and Chibougamau in the Abitibi region of Québec, Canada. The Mineral Resource Estimate (





MRE





) defined by Osisko, as disclosed in the news release dated February 17, 2021 is


supported by the technical report entitled “Preliminary Economic Assessment Update for the Windfall Project” dated April 26, 2021 (that includes Windfall Mineral Resource Estimate with an effective date  of November 30, 2020), and


assuming a cut-off grade of 3.50 g/t Au,


comprises 521,000 tonnes at 11.3 g/t Au (189,000 ounces) in the measured mineral resource category, 5,502,000 tonnes at 9.4 g/t Au (1,668,000 ounces) in the indicated mineral resource category and 16,401,000 tonnes at 8.0 g/t Au (4,244,000 ounces) in the inferred mineral resource category


. The key assumptions, parameters and methods used to estimate the mineral resource estimate disclosed in the February 17, 2021 news release are further described in the full technical report prepared by BBA Inc. in accordance with NI 43-101 and is available on SEDAR (



www.sedar.com



) under the Corporation’s issuer profile. The Windfall gold deposit is currently one of the highest-grade resource-stage gold projects in Canada and has world-class scale. Mineralization occurs


in


three


principal


zones:


Lynx,


Main Zone,


and


Underdog.


Mineralization is generally


comprised of


sub-vertical


zones


following


intrusive porphyry


contacts


plunging


to


the


northeast.


The r


esources are defined from


surface


to


a


depth


of


1,600


metres as it now includes the Triple 8 (T8) zone. The resources excluding T8 are defined from surface to a depth of 1,200 metres.


T


he deposit


remains


open along


strike


and


at


depth


.


Mineralization


has


been


identified


at


surface


in


some


areas


and


as


deep


as


2,625


metres in others with significant potential to extend mineralization down-plunge and at


depth.


About Osisko Mining Inc.



Osisko is a mineral exploration company focused on the acquisition, exploration, and development of gold resource properties in Canada. Osisko holds a 100% interest in the high-grade Windfall gold deposit located between Val-d’Or and Chibougamau


in


Québec


and


holds


a


100%


undivided


interest


in


a


large


area


of


claims


in


the


surrounding


Urban


Barry


area and nearby Quévillon area (over 2,700 square


kilometres).


Cautionary Note Regarding Forward-Looking Information



This news release contains “forward-looking information” within the meaning of the applicable Canadian securities legislation that is based on expectations, estimates, projections and interpretations as at the date of this news release. Any statement that involves predictions, expectations, interpretations, beliefs, plans, projections, objectives, assumptions, future events or performance (often, but not always, using phrases such as “expects”, or “does not expect”, “is expected”, “interpreted”, “management’s view”, “anticipates” or “does not anticipate”, “plans”, “budget”, “scheduled”, “forecasts”, “estimates”, “potential”, “feasibility”, “believes” or “intends” or variations of such words and phrases or stating that certain actions, events or results “may” or “could”, “would”, “might” or “will” be taken to occur or be achieved) are not statements of historical fact and may be forward-looking information and are intended to identify forward-looking information. This news release contains the forward-looking information pertaining to, among other things: the Windfall gold deposit being one of the highest-grade resource-stage gold projects in Canada and having world-class scale; the key assumptions, parameters and methods used to estimate the mineral resource estimate disclosed in this news release; the prospects, if any, of the Windfall gold deposit; timing and ability of Osisko to file a technical report for the mineral resource estimate disclosed in this news release; the timing and ability of Osisko, if at all, to publish a feasibility study for the Windfall gold deposit; the amount and type of drilling to be completed and the timing to complete such drilling; the focus of the remaining infill drilling; the trend of grade increase; the Lynx zone remaining open to expansion down plunge; upgrading a inferred mineral resource to a measured mineral resource or indicated mineral resource category; future drilling at the Windfall gold deposit; the significance of historic exploration activities and results. Such factors include, among others, risks relating to the ability of exploration activities (including drill results) to accurately predict mineralization; errors in management’s geological modelling; the ability of Osisko to complete further exploration activities, including (infill) drilling; property and royalty interests in the Windfall gold deposit; the ability of the Corporation to obtain required approvals; the results of exploration activities; risks relating to mining activities; the global economic climate; metal prices; dilution; environmental risks; and community and non-governmental actions. Although the forward-looking information contained in this news release is based upon what management believes, or believed at the time, to be reasonable assumptions, Osisko cannot assure shareholders and prospective purchasers of securities of the Corporation that actual results will be consistent with such forward-looking information, as there may be other factors that cause results not to be as anticipated, estimated or intended, and neither Osisko nor any other person assumes responsibility for the accuracy and completeness of any such forward-looking information. Osisko does not undertake, and assumes no obligation, to update or revise any such forward-looking statements or forward-looking information contained herein to reflect new events or circumstances, except as may be required by law.


CONTACT INFORMATION:


John Burzynski

Chief Executive Officer

Telephone (416) 363-8653



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